SPR comparison

SKi Pro compared to SPR

Surface plasmon resonance is a well known technique to study interactions of protein without labels. Like SKi Pro, the technique relies upon the fact that biomolecules have an inherent refractive index that is greater than water. In a sensor that is sensitive to refractive index changes, a protein binds, displaces water and a signal can be detected. The primary difference between the two techniques is that SKi Pro has much greater binding capacity and offers up the possibility of performing one-of-a-kind affinity capture-mass spectrometry (AC-MS) experiments.

Data compared

Often we are asked how measurements on SKi Pro compare to those on SPR. Prior to the introduction of SKi Pro we characterized multiple interactions, ranging from antibody-antigen interactions, to protein-small molecule interactions. We plotted these against each other and found very good correlation, as can be seen in the chart.

The surfaces of SPR and SKi Pro are quite different, and the optical interrogation technique also differs, yet matching the KD's is straightforward. SKi Pro, though has so much more capture capacity it allows for time-resolved AC-MS which SPR does not.

SKi Pro-SPR Correlation

Figure 1 Dissociation equilibrium constants from a variety of measurements for SKi Pro and SPR are compared.

Table 1 Comparing SPR to SKi Pro regarding various parameters.

ParameterSKi ProSPR
Chip Typenanoporous silicongold coated slide
Interrogationwhite light interferometrysurface plasmon resonance
Reference Typefully parallelserial (generally)
Fluidicson chipoff chip
Simple cloguser fixservice engineer
Protein capture>100 ng/µL<1 ng/µL
AC-MSon line, straight forwardoff-line, very difficult